Incandescent lamp stem



Oct. 22,1935. A; HQFMANN ET AL INCANDESCENT LAMP STEM Filed Dec. 3, 19312 Sheets-Sheet 1 I INVENTORS:

& Wm Wm WM, Kmad V CM M) (k ATTORNEYS Oct. 22, 1935; I A. HQFMANYN El AL9 3 INCANDESCENT LAMP STEM Filed Dec. 2 1-931 2 Sheatse-Sheet 2INVENTOR$ 8 Ptmwlwa-an),

PATENT OFFICE INCANDESCENT LAMP STEM Alfred Hofmann, Palisade, andVictor Anderson,

North Bergen, N. J., assig'nors toAlfred Hofmann & Company, West NewYork, N. J., a

corporation of New Jersey Application December 3,1931, Serial No.578,700

Claims.

This invention relates to incandescent lamp stems and the manufacturethereof, referring particularly to electric lamps in the nature of bulbsor tubes containing electrodes or filaments l and either exhausted ofair or filled with a particular gas, and whether for illumination, radioor other purposes. The invention is shown illustratively applied to thestem par'tof the modern types of incandescent filamentary lamp, the

: bulb or tube of the completed lamp being tipless,

and the air exhausting (and sometimes gas filling) of which is effectedthrough a small air pipe entering the lamp chamber through the stem.

:: The general objects of the present invention are to afford animproved lamp stem and resulting lamp, and improved method and means ofmanufacture thereof; Particular objects are to improve the lamp stem inregard to structure,

-; form and strength; to improve the exhausting or filling steps by theuse of a larger size air Pipe, and by entering such pipe into a lowerpoint in the lamp chamber; to afford an improved sealing of theleading-in wires; and to dispense 25, with. the preformed or tubularflare which is usually an element of the completed stem part.

A further object is to simplify and improve the manufacture of lampstems by dispensing with the customary steps of preforming the flare,

" from glass tubing, and separately preforming the filament anchor orpost when used, from a glass rod, and subsequently combining these andthe air pipe and leading-in wires into aunitary stem, and blowing aperforation for communication of the air pipe with the interior; thisimprovement permitting the manufacture of the complete stem part,containing the essential components, by a single operation of-moldingthe same from'molten glass, thereby to produce the complete stem,shaping it with body, with skirt or flared flange and with anchor post,combining with it the preformed air pipe, and sealing in the lead wiresand pipe, all in one operation and apparatus; resulting in cheapenedproducflvtion and improved structure of lamp stem and lamp.

Other and further advantages of the invention will be explained in thehereinafter following description of one or more illustrative embodi- 50ments thereof or will be understood to those conversant with thesubject. To the attainment of such objects and advantages the presentinvention includes the novel incandescent lamp stem, and the novelmethod and means of manufac- Bl' -ture thereof, and the novel featuresof procedure,

structure and 'detail herein illustrated or described.

In the accompanying drawings .Figure 1 is a side elevation of anincandescent lamp stem embodying the present invention, the position of5 the subsequently applied bulb or tube being indicated enclosing thelamp chamber in which are contained the stem and connected parts.

Fig. 2 is an edge elevation of the lamp stem of Fi 1. 10 Fig. 3 is a topplan view partly in horizontal section on the line 33 of Fig. 1.

Fig. 4 is a side elevation of a common form of incandescent lampembodying the features shown in Figs. 1 to 3 and completed to the extentof 15 the attachment of the filament and the insertion and fusion of thestem with the bulb and the exhaustion and sealing of the lamp.

Fig. 5 is a side elevation of a modified lamp stem; and Fig. 6 intransverse section shows a 20 further modification.

Fig. 7 shows in elevation another modified form. Fig. 8 in elevationshows still another form, and Fig. 9 a top View thereof.

Figs, 10, 11 and 12, in transverse section, show 25 various illustrativemodifications in the form of the stem body, for example to embody four,five or other plural number of lead wires.

Fig. 13 in top view, and Fig. 14 in elevation, show a modified form ofthe upper end of the 30 molded anchor post of Figs. 1-3; and Fig. 15 isa perspective, with variations.

Fig. 16 is a top view, and Fig. 17 is, an elevation of a modified formof lamp stem embodying this invention, with the preferred character ofmold; 85 ing means therefor indicated in dotted lines.

In respect to structure the present product differs radically andessentially from the usual lamp stem part, which is built up from a.preformed upright tubular glass flare, so called, 40 having its bottomend open and having its top end fused, flattened and closed to embed andseala. short length of the lead wires, and to receive and seal the smallair pipe extended upwardly through the length of the tubular flare,andto receive the preformed filament anchoring post. The presentinvention as distinguished therefrom may be described as consisting ofan upright body which preferably is not tubular but which on the otherhand is formed with a closed bottom, and such closed bottom having anintegral outstanding skirt for subsequent connection with the lamp bulb,and a preformed air pipe extended through and embedded and sealed insuch closed bottom and open thereabove for the subsequent exhaustion ofair from the lamp chamber, and one or two or a greater number of leadwires extended through and embedded and sealed in the closed bottom ofthe body and preferably also in the upper portion of the bodythereabove, the wires having therefore an extended length of sealing,and issuing from the body for subsequent attachment thereto of the lampfilament or electrode; and the structure is believed to be broadly newin the aspect of the stem with lead wires sealed therein, or the stemwith air pipe sealed therein, or both. The terms upright" and the likeare used in a relative sense assuming the longitudinal length of thelamp is held vertical with its base downward.

Referring in detail to the drawings, the particular embodiment shown inFigs. 1 to 4 comprises a lamp stem of glass or the like, the body 'ormain portion 20 of which may be described as upright, as it hassubstantial longitudinal extent or height in the direction of the lengthof the lamp. The body comprises mainly an upper portion 2| and a bottomor section 22, merging together, the bottom being disklike or otherwisetransversely closed, and the upper portion comprising the glass materialabove the bottom, being preferably of reduced cross section as comparedwith the bottom and preferably formed ofsubstantial height and with alaterally opening air recess as will be described. The closed section orbottom is shown as formed with an integral outstanding skirt 23 adaptedsubsequently to be fused and united with the bulb or container of thelamp chamber, such skirt being preferably flared downwardly. In a sensethe closed lower end or bottom section 22 of the stem body is a sort ofnucleus or center from which extend integrally the upper portion 2i, theskirt 23, and the air pipe to be described; any of which extensions maybe varied in shape or extent to suit any particular requirements.

In Fig. 1 the upper portion of the body is shown as constituted of aplurality of separate or spaced apart sides or columns, and when soformed the upper ends thereof are preferably connected by an integraltop 24. Enclosed by the columns, or formed otherwise, is shown an airrecess or laterally opening aperture 25 located in the body above thebottom, and the bottom is formed with an air perforation 26 shown asopening into the recess 25, thus giving communication to the air pipefor exhausting purposes. Below the bottom, when the skirt 23 is flared,is formed a concavity or underneath recess '21.

An air pipe 30 containing a through passage 3i is shown extendedthroughthe body bottom 22 and sealed therein, its passage 3i opening outthrough the perforation 26 into the lateral recess 25 and thus afiordingsubsequent communication between the inside of the lamp and theatmosphere for exhausting and filling purposes. While the air pipe mightbe formed in the molding process, it is preferably a preformed pipe ofcorrect length, inserted in the mold.

One or more lead wires 35 in this case two, are shown, extended throughthe bottom 22 and sealed therein, and preferably the lead wires arecarried interiorly through the upper portion 2i of the body, thus givingan extensive sealing length, which may be substantially the full heightof the body of the lamp stem. Exterior wire portions 36 constitute freeends for subsequent connection to terminal contacts, while interior freeends 31 issue from the upper part of the body to be subsequentlyshortened and disposed suitably for connection of any form of filamentor electrodes.

The description of the illustrated lamp stem is I substantiallycompleted by reference to the supporting extension or post 40, which isan optional feature but usually preferable to give support to the middleor other part of the filament of an illuminating lamp, or for supportingany other 10 electrode. The post, 40 is shown as extended upwardly fromthe upper portion 2| of the body or preferably directly from the centerof the top 24.

All of the portions thus far described are prefl5 erably constituted ofa unitary integral piece of glass or similar vitreous matter, with theexception of the lead wires which may be composed of dumet metal orother suitable conducting material; and the post 40 may be wholly orpartly an 20 attached component. The lamp bulb, tube or enclosing wall45 is-indlcated in Fig. 1, its lower portion 46 being shaped in byfusion and united to the outer edge of the skirt 23, after thecompletion of the stem and attachments. The lamp at 25 this stage isshown in Fig. 4, enclosing the evacuated or gas filled chamber 41, andthe air pipe I. being sealed off and closed at 32, while the wires carrythe filament 49, steadied by attachment to the anchor button 4| at thetop of the post ll. 30 which may have embedded anchor wires 42 for thepurpose.

The described lamp stem is not merely of high strength and practicalefllciency, but is of such form as to lend itself to eifective and largescale 35 manufacture by a molding process. molten or viscous glass beingforced under pressure into a properly constructed mold as will bedescribed. The advantages heretofore enumerated are attained. The leadwires 35 are sealed within the 40 bottom 22 of the stem and upwardlythrough the body clear to the point where they issue for attachment offilament.

While each lead wire might be composed of special or dumet wire having acoefficient of ex- 45 pansion about the same as that of glass, with thisinvention a lead wire may readily be employed built up of threelengthwise united sections. for example an outer length of copper, amiddle length of special or dumet wire and an interim 50 length ofnickel wire, the middle or special wire preferably being made longerthan usual and long enough to extend the full length for which the leadwire is embedded in the stem body.

The air pipe 30 is readily fused and sealed in 55 the stem bottom duringmolding, and its interior passage maintained open at the perforation 2'for communication with the recess 25. The air pipe is thus substantiallyshortened as compared with that in a lamp stem built up upon a tubular.0 flare, since the air pipe does not extend to the top but mayterminate directly at the upper side of the bottom 22 of the structure.Having a shorter projecting length the pipe is stronger, and it isreadily sealed off and closed, as indicated in Fig. 4, a temporary flameshield being located between the closing point 32 and the stem body. forexample shaped into the concavity 21 within the skirt 23, thus toprotect the stem body and skirt '0 and connected parts from injury fromthe sealing heat. A cylindrical shield can be applied surrounding thepipe and lead wires when fusing the skirt to the bulb.

By the disclosed arrangement the air pipe 2. 15

exhausts the lamp from a low or even the lowest point within the lampchamber, instead of from a point at the top of the usual stem. This isfound to be of advantage and assistance in removing vaporous and gaseouscontents of the lamp. No diificulty is encountered in ensuring theopening of the pipe passage 3| into the lamp chamber or lateral recess25, and the step is eliminated of supplementally fusing the stem at aninterior point while directing air pressure through the pipe to force aperforation. At the same time this invention permits an air pipe to beemployed of substantially larger diameter than usual, in fact as largeas desirable up to the point of conflict with the lead wires.

Before describing an illustrative method of production, the modifiedstructures shown in Figs. 5 etc. will be referred to, understanding thatthe principles may be used in greatly varied forms and that theillustrated forms are merely examples. One modification is the omissionof the anchor or supporting post, as when a filament is employed thatneeds no intermediate support, and Fig. 5 shows such modification. Thisfigure shows also that the lateral recess 25 may be varied in size, itbeing shown much shortened. Otherwise the structure is like Figs. 1-3,and Fig. 3 represents a section taken on the line 33 of Fig. 5.

The lateral aperture 25, or the lower portion of it, represents a lug orabutment, or an opposed pair of them projecting in the mold; the top endof the air pipe 30 abutting against the same, thus insuring that the airpipe is kept open and com- .municates with the recess. Preferably themold is fed with glass adjacent to this point and a portion of therecess 25 or 25 may represent a plunger operable to move through themold and cut off the supply; or such movable plunger may at firstconstitute the abutment for the pipe 39 and subsequently move across themold and cut off the flow. The form shown in Figs. 1-4 has beenmanufactured by the use of a movable plunger adjacent to a fixedabutment, or rather opposed abutments or lugs, in the mold, thus givingthe elongated recess 25, but these two mold parts, the plunger and lugs,might be non-adjacent, so as to form one recess for the abutment and airpipe and a second one for the plunger, the form shown in Figs. 1-4however giving minimum weight consistent with strength and otherrequirements.

Instead of employing opposed abutments to produce a through recess as inFigs. 1-5 a mold abutment. at one side only might be employed, affordingthe result shown in Fig. 6, considered as a cross section at the line 33of Fig. 5, the body 2| being completely closed at the far side and therecess 25 confined to the near side but having sufficient extent to givea clear air opening for the perforation 25.

In the form shown in Fig. 7 the cross piece or top 24 of the stem bodyis omitted, so that there remain two spaced apart columns 2|constituting the upper portion of the body, with a. recess 25 betweenthem into which the perforation 26 enters.

In Figs. 8 and 9 the stem body is reduced in height by the omission ofmuch of the upper portion shown in the other figures, the short bodyhowever still comprising the closed bottom 22 and the upright portion 2|thereabove. No lateral recess is here necessary as the perforation 26opens upwardly directly into the lamp chamber. The outlying flange orskirt 23 is not belled or flared downwardly as in Figs. 1-7, but isshown substantially fiat or even shaped slightly upwardly at the rim.

Fig. 10 indicates a cross section view of a modified lamp stem, whichmay be considered as taken substantially at the section line 33 of Fig.5. In this case four wires 35 are shown and the stem body 2| is shapedto enclose and embed these and to terminate with a closed bottom 22extended into the fiange or skirt 23. The air per foration or exit 26 ofthe air pipe is shown delivering into a lateral recess 25 preferablytaking out of one side only of the stem body. Fig. 11 shows a differentform on the same principles, five wires 35 being shown extending throughthe 15 body 2| and the lateral recess providing communication for theperforation 26 Fig. 12 shows a case where eight lead wires 35 may beembodied in the stem body 2|, the body here as before being formed witha lateral communicating 0 recess 25 for the perforation 26.

The Fig. 11 form can be molded as described, while the Figs. 10 and 12forms would require a special mold with side parts laterally retractingfrom the reentrant curves at the sides. 25

As a new article of manufacture the lamp stem hereof may be described ascomprising a skirt or flare section 22, 23 for subsequent fusion to alamp bulb, said section being relatively shallow or short in alongitudinal direction, combined with 30 an exhaust pipe 30 projectingintegrally near the axis of the stem at the exterior side of said skirtsection, said skirt section being transversely closed except as to theair passage 3| in said exhaust pipe, which passage extends through theskirt section and is open near the axis at the interior thereof forsubsequent exhaustion of air; also a body portion 20 projectingintegrally at the interior side of said skirt section, said body portionbeing relatively deep or long in a longitudinal direction, and having anopen recess 25 with which the passage 3| connects near the axis, andleadwires 37 extended through said skirt section and longitudinallyembedded and sealed in said body portion. Except for the preformedexhaust pipe, the glass parts, namely the skirt section and bodyportion, preferably consist of a unitary piece of molded glass, withwhich the pipe is integrally fused, and in which the leadwires aresealed; and the manufacturing may be practically performed by moldingoperations and apparatus such as originally fully described andillustrated in this application.

For convenience the molding shape of a molding plunger 69 and lugs 6|are indicated in dotted lines on Fig. 1, these combining to form thecentral or lateral recess 25 of the lamp stem body. By dispensing withone of the lugs El and deepening the other the recess thereof will beunilateral as in Fig. 6, or in Figs. 10, 11 and 12.

Figs. 13 and 14 show a modification in the anchor post 40 as otherwiseshown in Figs. 1-3, indicating that with this invention the post may bemolded with the rounded button or top 4| as seen in Fig. 4, and theanchor supports or supporting wires 42 embedded in the button during themolding process; this readily being accomplished by drilling therequired number of small bores into which the wires 42 are insertedbefore the molding, leaving a small projecting end, but arranged toavoid contact or approach of one to another. In the Fig. 15 form theanchor wires are in greater number than in Fig. 14, and are setlongitudinally to the post, subject to being bent to any required anglein completing the lamp.

Figs. 16 and 17 show a lamp stem wherein the body 20 has no lateralaperture, it being hollow, open at the top, and round or square or otherhollow shape, with six or other number of lead wires 35' carriedvertically through it, and with the preformed air pipe 30 opening at 26into the lower end of the wall or interior space of the hollow body. Themolding arrangements may be as indicated in dotted lines. The mold lineor division between the upper and lower mold blocks may be somewhatabove the center at one side and below at the other. This permits thehopper 52' and gate 5| to be placed laterally, and the plunger 53operated therein; which in turn allows the cut off plunger 69 to bearranged for insertion. between the gate and the mold cavity, thus nothaving to cross the mold space or interrupt the continuity of the wallof the stem body.

There have thus been described an incandescent lamp stem and a means andmode of manufacture thereof embodying the principles of the presentinvention; and since various matters of procedure, structure and detailmay be modified without departing from the principles it is not intendedto limit the invention to such features except to the extent set forthin the appended claims.

What is claimed is:

1. As an article of manufacture a lamp stem comprising: a skirt or flaresection for subsequent fusion to a lamp bulb the same being relativelyshallow or short in a longitudinal direction, an exhaust pipe projectingintegrally near the axis of the stem at the exterior side of said skirtsection, said skirt section being transversely closed except as to theair passage in said exhaust pipe which passage extends through the skirtsection and is open near the axis at the interior thereof for subsequentexhaustion of air, a body portion projecting integrally at the interiorside of said skirt section the same being relatively deep or long in alongitudinal direction, and having an open recess with which saidpassage connects near the axis of the stem and leadwires extendedthrough said skirt section and longitudinally embedded and sealed insaid body portion.

2. A lamp stem as in claim 1 and wherein the skirt section and bodyportion are constituted of a unitary piece of molded glass and theexhaust pipe being a preformed glass pipe fused integrally with saidskirt section. a

3. As an article of manufacture a lamp stem comprising: a skirt or flaresection for subsequent fusion to a lamp bulb the same being relativelyshallow or short in a longitudinal direction, an exhaust pipe projectingintegrally at theexterior 10 side of said skirt section, said skirtsection being transversely closed except as to the air passage in saidexhaust pipe which passage extends through the skirt section and is openat the interior thereof for subsequent exhaustion of air, a body 16portion projecting integrally at the interior side of said skirt sectionthe same being relatively deep or long in a longitudinal direction, andformed with a laterally open recess within which opens such air passage,and leadwires extended 20 through said skirt section and longitudinallyem-- bedded and sealed in said body portion.

4. A lamp stem as in claim 3 and wherein the body portion is formed witha recess opening laterally in a plurality of directions dividing the 25body portion into spaced columns within which the leadwires areembedded.

5. As an article of manufacture of lamp stem comprising: a shallow flaresection for subsequent fusion to a lamp bulb, an exhaust pipe fused withand projecting at the exterior side of said flare section, said flaresection being transversely closed except as to the air passage in saidexhaust pipe which passage extends through the flare section and is openat the interior thereof for 86 subsequent exhaustion of air, a bodyportion formed integrally with and projecting longitudinally at theinterior side of said flare section, and' leadwires extended throughsaid flare section and longitudinally embedded and'sealed in said body40 portion, and issuing therefrom at an interior point, said bodyportion provided with an interior extension beyond the point of issuanceof the leadwires for the support of an electrode.

ALFRED HOFIVIANN. 5

VICTOR ANDERSON.

